Gear grinding machine



y 1 M. R. ANDERSON 2,469,807

GEAR GRINDING MACHINE Filed May 16, 1946 i 4 Sheets-Sheet 1 m 7 as INVENTOR.

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May 10, 1949. M. R. ANDERSON 2,469,807

GEAR GRINDING MACHINE Filed May 16, 1946 4 Sheets-Sheet 2 IN VEN TOR. yi/r Z fizzle/:54.

y 1949- M. R. ANDERSON 2,469,807

GEAR GRINDING MACHINE Filed May 16, 1946 r 4 Sheets- Sheet 4 I /7 a: "Hll|l|||l Ill as lllll II I llllll 56 9; JNVENTOR.

{24/1227 Z i/z/erJa/z Patented May 10, 1949 UNITED STATES PATENT OFFICE GEAR GRINDING MACHINE Marvin R. Anderson, Grosse Pointe Park, Mich., assignor to Michigan Tool Company, Detroit, Mich., a corporation of Delaware Application May 16, 1946, Serial No. 670,254

20 Claims. (Cl. 51-71) This invention relates generally to grinding machines, and it has particular relation to a grinding machine having a grinding wheel of substantial axial length with a series of teeth formed in the annular face thereof which are of a straight rack tooth form in a cross-sectional profile, permitting grinding of more than one tooth on a gear each time the same axially traverses the grinding wheel.

In the present practice of finishing gear wheels by means of grinding, it is customary to finish the same by means of a generative action between the grinding wheel and the gear teeth, but the same is accomplished by individually finishing each gear tooth. In such process, each tooth is indexed to the grinding wheel until the entire gear is finished. By this means, after all the flanks on one side of the gear teeth have been completely finished, it is necessary to reverse the gear and in a similar manner finish the flanks on the opposite side. As can be appreciated, such finishing process requires considerable time and must of necessity result in increased cost of production.

Therefore, a grinding machine which will finish both flanks of a gear tooth and with which more than one gear tooth may be ground on each stroke of a gear axially across the grinding wheel will have considerable appeal to gear manufacturers.

One object of the present invention is to provide a gear finishing machine with which more than one gear tooth is finished as the gear axially traverses the grinding wheel due to the generative action between the teeth on the grinding wheel and the gear being finished.

Another object of the present invention is to provide a gear finishing means with which both flanks of a gear tooth may be finished as the gear to be finished engages the grinding wheel.

Another object of the invention is to provide an improved and efiicient gear finishing machine for the purpose mentioned which may be used to finish a gear with extreme accuracy and which may be operated by semiskilled or relatively unskilled labor to accomplish this desirable result.

A still further object of the present invention is to provide such gear finishing machine for this purpose which has a crush dresser for dressing the grinding wheel at convenient intervals.

Other objects of the invention will become apparent from the following specification, from the drawings relating thereto, and from the claims hereinafter set forth.

For a better understanding of the invention, reference may be had to the drawings, wherein:

Figure 1 isa front elevation of a grinding machine embodying the improvements of the present invention.

Figure 2 is a section taken on line 2-2 of the machine illustrated in Figure 1 showing the operating mechanism for the grinding machine.

Figure 3 is a section on line 3-3 of Figure 1 illustrating the mechanism for reciprocating the upper carriage.

Figure 4 is a section taken substantiallyon line 4-4 of Figure 2, illustrating the grinding wheel and adjusting means for the same.

Figures 5 to 9, inclusive, are enlarged diagrammatic sketches illustrating the operating sequence of the index mechanism included within circle 5 of Figure 1.

Figure 10 is a section on line ill-l0 of Figure 3.

According to the present invention, a gear to be finished is mounted upon a rotatable and reciprocable spindle. This spindle is reciprocated laterally and a master gear mounted thereon meshes a master rack effecting rotation of the spindle and the workpiece as the same engages the straight rack teeth on the rotating grinding wheel. Such movement effects the workpiece to roll in the straight rack teeth of the grinding wheel serving to cause involute surfaces to be generated on the flanks of the workpiece. The reciprocation of the spindle in a, direction normal to the lateral reciprocation thereof permits a workpiece having wide flanks to have the entire flank finished as the gear rolls across the teeth of the grinding wheel. In the case of a gear having a circumference equal to or less than the axial length of grinding wheel, it is possible to finish the entire gear without indexing. However, in the case of a gear having a circumference greater than such axial length, indexing is required. For

this purpose, indexing mechanism is provided to index the workpiece upon each reciprocation of the spindle in the lateral direction. However, it is always possible to finish more than one tooth of the gear before this indexing takes place. The

machine also provides a crush dresser carried on the upper table in such position that it may be moved into mesh with the grinding wheel whenever necessary to dress the same during th grinding operation.

For a more complete description of the machine of this invention, reference is made to the figures in which a base is generally indicated as i. base may be a hollow integral structure of suitable size and proportion to house interiorly thereof a Such I 3 driving mechanism for the grinding machine. This base also provides for supporting the grind ing wheel and the driving mechanism therefor on the upper, exterior surface of the same.

On the forward face of said base, which is at the left as viewed in Figure 2, a machined surface 2 is provided. To accomplish the finishing of the entire flank width of a gear to be finished, carriage 3 is mounted on this surface 2, for reciprocation in a direction normal to the axis of rotation of the grinding wheel. In order to provide for this reciprocation, a suitable prime mover in the form of an electric motor 4 is mounted within base I. coupling 6 effecting rotation of eccentric 'l secured to the opposite end of said shaft 5. It will be observed, that as eccentric I rotates within the opening provided therefor in bearing block 8, carriage 3 will reciprocate inasmuch as said bearing block is secured by a plurality of bolts 9 to Such motor drives shaft 5 by means of said carriage 3. A locating pin ltlis adapted to be received within opening H provided in carriage 3 for movement into mating opening l2 provided in the base I.' Obviously, such locating pin is not pressed into opening [2 during reciprocation of the carriage, but is only used while the grinding wheel is dressed, as will hereinafter become more clear.

. For reciprocating the gear to be finished in a direction parallel to the axis of rotation of the grinding wheel to effect the finishing of the gear tooth flanks, work carriage I3 is provided. This carriage is slidably mounted for reciprocation in this manner upon machined surface I 4 and slideway l5 at the top of carriage 3. Carriage l3 provides a suitable housing IS in which spindle I1 is journaled for rotation. This spindle rotatably supports gear l8 to be finished for reciprocation with carriage l3. Supported in this position, it will be seen that gear l8 meshes the grinding wheel [9.

In order to reciprocate carriage [3 in the manner described, suitable driving means are provided. As described and illustrated inthis speciflc application of the invention herein disclosed, this driving means is manually operable. However, it will be apparent that such driving might well be accomplished by other means such as, for example, an electric motor. To accomplish this reciprocation, a conveniently accessible hand wheel is provided to rotate shaft 2| with integral worm 22 thereon. This worm 22 drives worm wheel 23 and shaft 24 connected thereto to effect rotation of pinion 25 on the opposite end of said shaft 24. It will be observed that said pinion 25 meshes rack 26 integrally connected to the lower surface of carriage l3. Thus, as gear 25 rotates, carriage I3 slidably moves in one direction and as the rotation of gear 25 is reversed, carriage l3 moves in an opposite direction to accomplish the reciprocation of the same.

During reciprocation of carriage l3 as described in the foregoing, rotation of gear I8 is accomplished by master gear 21 which meshes master rack 28. Such'master gear, which is a precisely finished counterpart of gear I8, is integrally connected to spindle I! in position to mesh said rack 28. The master rack 28 is anchored to carriage 3 and it will be observed that both master gear and master rack reciprocate with carriage 3 thereby constantly maintaining their alignment relative to-each other. As work carriage l3 reciprocates axially of the grinding wheel, the master gear 21 rotates inasmuch as the master rack 28 does not reciprocate with carriage I3.

4 Such rotation of the master gear effects the rotation of spindle l1 and gear 18. The combined reciprocation and rotation of gear 18 serves to cause said gear to roll as it meshes teeth 29 on grinding Wheel l9, effecting the generation of an involute surface on each flank of the teeth of said gear during reciprocation thereof axially of said grinding wheel. It will also be observed that the reciprocation of the work gear in a direction normal to the axis of rotation of the grinding wheel l9, by means of carriage 3, will effect the finishing of the entire width of the tooth fiank on such work gear.

In order to mount grinding wheel [9 in a position to engage gear 18, base I provides at 30 a ,machined surface and at 3| a slideway to receive carriage 32 of the grinding head. Thiscarriage provides upwardly directed arms 33 and 34 which carry bearing housings 35 and 36, respectively. Roller bearings 31 and 38 are mounted within bearing housing 35 and held in spaced relationship with respect to each other by-means of a spacer 39. In a similar manner, roller bearings 40 and 4| are received in the bearing housing 36 and held in spaced relationship with respect to each other by means of spacer 42. These bearings rotatably support shaft 43 to which grinding wheel I9 is mounted by any suitable means such as the annular collars 44 and 45. Driving of this grinding wheel-is accomplished by means of a driving motor 46 mounted on said carriage 32. Such motor drives endless belts 41 and pulley 48 keyed at 49 to shaft 43 which rotatably supports said grinding wheel l3.

Up to this point, no mention has been made of the means for moving the grinding wheel relatively to gear l8. Meansare provided for initially positioning the grinding wheel with respect to the gear to be finished and also for feeding said wheel as the grinding operation proceeds.

To initially position the grinding head, a slide 50 is mounted immediately below and centrally ofcarriage.32 to slidably move upon machined surface 30. This slide carries pin 5| which supports lever 52 extending through a rectangular opening 53 in said slide. As will hereinafter become more clear, such lever is designed to oscillate about pin 5| and bear against swivel block 54 which registers in the upper forked end 55 of such lever. Said swivel block is rotatably supported by pin 56 between depending ears 51 and 58 of cover plate 59 over rectangular opening 60 in carriage 32. The lower forked end 6| of lever 52 retains lead nut 62 which threadably engages feed screw 63 journaled for rotation in bearings 64 and 65, housed within the hollow interior of outer shaft 66, and bearing 61 mounted in bearing block 68. This hollow outer shaft is in turn journaled for rotation in bearings 69 and 10 supported by housin 1| anchored to extend outwardly from base I. A lead nut 12 is anchored to the bottom of slide 50 to threadably engage feed screw 13 journaled for rotation in bearings I4 and 15 which are supported by base I and bearing block 63,

respectively. Thus, as such feed screws are simultaneously rotated, lead nut 62 andlead nut 12 move relative to their respective feed screw. When this occurs, slide 50 shifts, carrying with it lever 52, efiecting forked end 55 thereof to bear against swivel block 54 for shifting carriage 32 of the grinding head. Such simultaneous rotation of these feed screws is accomplished by locking handwheel 16, integrally connected to feed screw 63, to handwheel 11 secured to outer shaft 66. To provide for this locking, handle 18 on 8 handwheel I8 may be moved inwardly toward handwheel I'I until the end of such handle registers within opening I9 provided in handwheel 'II. Locked in this manner, these handwheels may be simultaneously rotated by means of handle l8, driving feed screw 63 and outer shaft 66 with gear 88 thereon for driving gear 8| and feed screw I3.

After the grinding head is thus placed in predetermined, adjusted position, handle I8 is withdrawn from handwheel I1 and said handwheel may be positively locked against further rotation by means of thumb screw 82. Such screw may be turned until the sharpened end thereof engages the handwheel to prevent further rotation.

During the grinding operation, feeding of the grinding head to move the wheel toward or away from gear I8 is accomplished by means of lever 52. As stated in the foregoing, such lever oscillates about the pin It will be observed that as feed screw I3 is separately rotated by means of handwheel I6, lead nut I2 will progress along said feed screw. This movement of the feed screw effects lever 52 to move arcuately about pin 5I and bear upon swivel block 54 efiecting only carriage 32 to shift as slide 58 is locked in position as previously described.

The extent ofthis feeding movement may be accurately and precisely controlled by means of stop 83. This stop threadably engages a downwardly directed tab 84 on carriage 32 in position to contact the end of slide 58 for limitin the extent of the inward movement of said carriage.

A lock nut 85 threadably engages the other end of the stop and when tightened against tab 84 locks the stop accurately and precisely in position.

As stated hereinbefore, when the circumference of the pitch circle of gear I8 is equal to or less than the length of the grinding wheel I9, all of the teeth on said work gear will contact the grinding wheel twice during a reciprocation of which indexes the work gear sufficiently to per-.

mit all of the teeth thereon to contact the grinding wheel. Such indexing is accomplished by means of an index gear 86 connected to spindle H in position to mesh a slidable index rack 81.

As best seen in Figure 5, only the master pinion and rack are engaged when carriage I3 begins a stroke toward the left. However, as carriage I3 progresses in this direction, the index pinion engages the index rack while the master pinion and rack are still meshing. The teeth on the index pinion and rack are ground slightly undersize to prevent interference with the rotation imparted to spindle I1 during this interval. As motion continues in .the same direction, it will be observed that dog 88 carried by the bell crank shaped lever 89, which is pivotally mounted at 98 to the lower end of spindle housing I6, will come into contact with the index rack which is frictionally held by friction button 9|. When this occurs, the master pinion and master rack have become disengaged. leaving only index pinion and rack in engagement. There is still no rotation effected by the index gear and rack inasmuch as dog 88 moves the index rack at the same rate of travel as spindle I'I progresses. In this manner, index rack 81 is pushed to its left-hand position where it is retained by friction button 9|. Thus, as carriage l3 begins a return stroke toward the right, the index gear rolls on the index rack to effect indexing rotation of spindle I'I .until the bell crank shaped lever 93, which is pivotally mounted at 94 to spindle housing I8, contacts the index rack to return the same to its light-hand location in readiness for the forthcoming stroke toward the left. In this manner, all of the teeth of a gear having a pitch circle circumference greater than the length of grinding wheel I9,.are indexed into contact with teeth 29 on said wheel to accomplish the finishing .of each flank of each gear tooth.

As a means for, accurately positioning each work gear during the loading thereof, the machine provides a plunger 95, the tapered end 98 of which may be introduced between adjacent flanks of gear teeth. Such pin is supported within the annular housing 91 in awithdrawn position. An annular compression spring 98 encircles said pin to abut shoulder 99 thereon and end I88 of housing 91 for maintaining the pin in this position. During the loading operation,

this pin is forced inwardly against spring 98 byplunger engages adjacent flanks of the gear teeth to accurately position the same.

In order to dress the grinding wheel at convenient intervals, a crush dresser I is also mounted on carriage I3. For this dressing operation, the reciprocation of carriage 3 is discontinued and locating pin I8 is pressed into opening I2 provided in base I as hereinbefore described, locking said carriage positively and accurately in position for the dressing of the wheel. To bring the crusher I85 into position opposite the grinding wheel I9, it is necessary to over-run the indexing mechanism. This maybe accomplished after dog 92 is removed bywithdrawing pin I88 which holds that portion of lever 93 carrying said dog. When this is done, table I3 may be moved toward the right, as viewed in Figure 1, and said dresser brought into engagement with the grinding wheel. Key slots I81 and I88 in carriage I3 and base I, respectively, may be used to mount dogs a or other means for accurately and precisely locatin a direction toward or away from the grinding A wheel. Such adjustment provides for wear of the grinding wheel and it will 'be appreciated that as this wear occurs, the crush dresser may be moved inwardly. Such adjustment is accomplished by means of screw I I8 which is journaled for rotation in slide I89 and threadably engages the tapped opening in base I. Obviously, as this screw is rotated, the slide must shift inwardly or outwardly, depending upon the direction of rotation of the screw. The amount of this adjustment may be accurately and precisely controlled by means of a stop II I. Such stop threadably engages slide I89 and is adapted to bear against 7 accurately in position. when slide H9 has been precisely positioned, the same may be lockedthereat by means of bolt H3 which is adapted to extend through opening H4 in said slide to theadably engage a tapped opening in base I. Upon tightening bolt 3, it will be quite apparent that the crush dresser will be accurately and precisely locked in predetermined, adjusted position. After the dressing operation has been completed, the dresser I05 may again be removed to its left-hand position and dog 92 replaced on the machine in preparation for a continuation of the grinding operation.

Thus, with a grinding machine as described in the foregoing, it will be observed that it is possible to grind more than one tooth of a gear without indexing each individual tooth to the grinding wheel.

It will be clear from the foregoing description that the grinding machine shown in the drawings and described above has been illustrated and described in rather specific detail. Obviously, many modifications, changes, and departures from the above described construction may be made without departing from the generic spirit and scope of the invention as set forth in the subjoined claims.

What is claimed is:

1. In a gear grinding machine, a base, a grinding head mounted thereon, said head including a rotatable, formed grinding wheel of substantial axial length and driving means therefor; a carriage slidably mounted on said base, driving means to effect reciprocation of said carriage in a direction perpendicular to the axis of rotation of the grinding wheel, said carriage slidably supporting a second carriage, said second carriage reciprocating with said first named carriage and independently thereof in a direction parallel to the axis of rotation of the grinding wheel, means to effect said independent reciprocation of said second carriage, a spindle mounted on said second carriage, said spindle adapted to rotatably support a gear, and means operatively associated with said spindle to eiIect rotation of the gear during independent reciprocation of the second carriage, the combined reciprocation and rotation effecting the gear to roll as the same engages the grinding wheel while the reciprocation of the first carriage effects the entire flank width of each gear to contact the grinding wheel.

2. In a gear grinding machine, a base, a grinding head mounted-thereon, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having annular grooves formed on the periphery thereof, and means to drive said wheel; a carriage slidably mounted on said base, driving means to efiect reciprocation of said carriage in a direction perpendicular to the axis of rotation of the grinding wheel, said carriage slidably supporting a second carriage, said second carriage reciprocating with said first named carriage and independently thereof in a direction parallel to the axis of rotation of the grinding wheel, means to effect said independent reciprocation of said carriage, a spindl mounted on said second carriage, said spindle adapted to rotatably support a gear, and means operatively associated with said spindle to effect rotation of the gear during independent reciprocation of said second carriage, the combined reciprocation and rotation efiecting the gear to roll as the sam engages the annular grooves of the grinding wheel while the reciprocation of the first carriage effects the entire flank width of each gear tooth to contact the grinding wheel.

3. In a gear grinding machine, a base, a grinding head mounted thereon, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth of a straight rack tooth form in cross-sectional profile, and means to drive said wheel; a carriage slidably mounted on said base, driving means to effect reciprocation of said carriage in a direction perpendicular to the axis of rotation of the grinding wheel, said carriage slidably supporting a second carriage, said second carriage reciprocating with said first named carriage and reciprocating independently thereof in a direction parallel to the direction of rotation of the grinding wheel, means to effect said independent reciprocation of said second carriage, a spindle mounted on said second carriage, said spindle adapted to rotatably support a gear to be finished, a master gear on said spindle, and a master rack on said first named carriage adapted to mesh said master gear for effecting rotation of the gear to be finished during the independent reciprocation of the second carriage, said combined rotation and reciprocation effecting the gear to be finished to roll as the teeth thereon engage the teeth on the grinding wheel serving to cause an involute surface to be generated on the flanks of more than one of the teeth of the gear to be finished while the reciprocation of the first carriage effects the entire flank width of each gear tooth to contact the grinding wheel.

4. In a gear grinding machine, a base, a grinding head mounted thereon, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth of a straight rack tooth form in cross-sectional profile, and means to drive said wheel; a carriage slidably mounted on said base, driving means to effect reciprocation of said carriage in a direction perpendicular to the axis of rotation of the grinding wheel, said carriage slidably supporting a work carriage, said work carriage reciprocating with said first named carriage and reciprocating independently thereof in a direction parallel to the axis of rotation of the grinding wheel, means to effect said independent reciprocation of said work carriage, a spindle mounted on said work carriage, said spindl rotatably supporting a gear to be finished,

and means to rotate said gear to be finished as the work carriage independently reciprocates, the combined rotative and reciprocative movements efiecting the gear to be finished to roll as the teeth thereon mesh with the rack teeth on the grinding wheel to finish both flanks of the gear teeth while the reciprocation of the first named carriage effects th entire flank width of each tooth to contact the grinding wheel. 7

5. In a gear grinding machine, the combination with a base of a grinding head slidably mounted thereon, said head including a rotatable grinding wheel, and driving means therefor; a work carriage, means on said base for slidably mounting said work carriage for reciprocation in a direction parallel to the axis of rotation of the grinding wheel, feeding means to slidably move the grinding wheel toward and away from the work carriage, said means including a rotatable feed screw, a lead nut threadably engaging the same, an arcuately movable lever operatively associated with said grinding head and adapted to be oscillated by said lead nut, and means to effect rotation of said feed screw.

6. In a gear grinding machine, the combina- I tion with a base of a work carriage, means on said base mounting said carriage for reciprocation, a spindle housing 'on said carriage, a spindle shaft joumaled for rotation in said housing, a master pinion and an index pinion integrally connected to said spindle shaft, a master rack and a shiftable index rack mounted on said work carriage mounting means, said racks being positioned to mesh their respective pinions, means to effect reciprocation of the work carriage, said index pinion -eil'ecting rotation, of a spindle at the beginning of one stroke in each reciprocation of the work carriage, said master pinion effecting all further rotation of the spindle throughout the remainder of each reciprocation and dogs carried by said spindle housing adapted. to altemateiy contact the index rack for shifting the same.

7. In a gear grinding machine, the combination of a base with a work carriage, means on said base mounting said carriage for reciprocation, a spindle housing on said carriage,a spindle shaft journaled for rotation in said housing, a master pinion and an index pinion integrally mounted on said spindle shaft, a master rack and a shiftable index rack mounted on said Work carriage mounting means, each rack being positioned to mesh its respective pinion, means to effect reciprocation of the work carriage, said index pinion effecting rotation of the spindle at the beginning of one stroke in each reciprocation of the work carriage, the master pinion effecting all further rotation of the spindle throughout the remainder of said reciprocation, dogs carried by said spindle housing adapted to alternately contact the index rack for shifting the same, and a friction button to hold the index rack while the index pinion eiiects rotation of the spindle.

8. In a gear grinding machine, the combination of a base with a work carriage, means on said base mounting said carriage for reciprocation, a spindle housing on said carriage, a spindle shaft journaled for rotation in said housing, a master pinion and an index pinion integrally connected to said spindle shaft, 21 fixed master rack and a shiftable index rack mounted on said work carriage mounting means, said racks being positioned to mesh their respective pinions, means 'pinion and an index pinion secured to said spinmeans, said racks being positioned to mesh their to sheet reciprocation of the work carriage, dogs carried by said spindle housing adapted to alternately contact the index rack for shifting the same in timed relation with the work carriage, and a friction button to hold the index rack during part of each stroke of the work carriage.

9. In a gear grinding machine, the combination of a base with a work carriage, means on said base mounting said carriage for reciprocation, a spindle housing on said carriage, a spindle shaft journaled for rotation within said housing, a master pinion and an index pinion integrally connected to said spindle shaft, a fixed master rack and a shiftable index rack mounted on said work carriage mounting means, said racks beingrespective pinions, said master rack being out of engagement with the master pinion for apart of one stroke of the work carriage during which interval the index pinion engages the shifting index rack and travels therewith efiecting no rotation of the spindle, dogs carried by said spindle housing adapted to alternately contact the index rack for shifting the same in timed relation with the work carriage, and means to efiect reciprocation of the work carriage.

1l.In a gear grinding machine, the combination of a base with the work carriage, means on said base mounting said carriage for reciprocation, a spindle housing on said carriage, a spindle shaft journaled forrotation in said housing, a master pinion and an index pinion secured to said spindle shaft, a fixed master rack and a shiftable index rack mounted on said work carriage mounting means, said racks being positioned to mesh their respective pinions', each of said pinions being in mesh with their respective racks for a part of one stroke in each reciprocation of the work carriage during which interval the index rack moves in timed relationship to the work carriage and the master pinion alone effects rotation of the spindle, and means to effect reciprocation of the work carriage.

12. In a gear grinding machine, a base, a grinding head mounted on said base, said head including a rotatable formed grinding wheel of substantial axial length, driving means for rotating said grinding wheel, means mounted on said base for reciprocation in a direction parallel to the axis of rotation of said wheel and in a direction perpendicular to the axis of rotation of said wheel, means for rotatably supporting a gear to be ground on said reciprocating means, and means for rotating said gear during said parallel reciprocation so as to cause said gear to roll as it engages said grinding wheel while the perpendicular reciprocation thereof causes the entire flank width of each gear tooth to contact the grinding wheel.

13. In a gear grinding machine, a base, a grinding'head mounted thereon, said head. including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth of straight rack tooth form in cross-sectional profile, means for driving said grinding wheel, means mounted on said base for reciprocation in a direction perpendicular to the axis of rotation of said wheel .and in a direction parallel to the axis of rotation of said wheel, means for rotatably supporting a gear to be ground on said reciprocating means and in a position for engagement by said grinding wheel, whereby when said wheel engages said gear said parallel reciprocation of the gear will cause said gear to roll on said grinding wheel, while the reciprocation of said gear in the perpendicular direction will cause the entire flank width of each gear tooth to contact the grinding wheel.

14. In a gear, grinding machine, a base, a grinding head mounted thereon, said grinding head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth of a straight rack tooth form in cross-sectional profile, driving means for said grinding wheel, a car-- riage slidably, mounted on said base, driving means to eifect reciprocation of said carriage in a direction perpendicular to the axis of rotation of the grinding wheel, said carriage slidably supporting a second carriage, said second carriage reciprocating with said first-named carriage and independently thereof in a direction parallel to the axis of reciprocation of the grinding wheel, means to efiect said independent rotation of said second carriage,- means for rotatably supporting a gear to'be ground on said second carriage and in a position to be engaged by said grinding wheel, the reciprocation of said second carriage causing the gear'to roll as it engages the grinding wheel while the reciprocation of said first carriage causes the entire flank width of each gear to contact the grinding wheel.

15. In a gear grinding machine, a base, a grinding head mounted on said base, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth of a straight 4 rack tooth form in cross-sectional profile, means to rotatably drive said wheel, a carriage slidably mounted on said base, driving means to effect reciprocation of said carriage in a direction perpendicular to the axis of rotation of the grinding wheel, said carriage slidably supporting a second carriage, said second carriage reciprocating with said first-named carriage and independently thereof in a direction parallel to the axis of rotation of the grinding wheel, means to eflect said independent reciprocation of said second carriage, means for rotatably supporting a gear to be finished by said grinding wheel on said second carriage, feeding means to slidably move said grinding wheel toward and away from said work carriage, the reciprocation of said work carriage causing said gear to roll as the same engages the teeth of the grinding wheel while the reciprocation of the first carriage operates to expose the entire flank width of each gear tooth to the surface of the grinding wheel.

16. In a gear grinding machine, a base, a grinding head mounted thereon, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spacedannular teeth of a straight rack tooth form in cross-sectional profile, means to drive said wheel, a carriage slidably mounted onsaid base, drivin means to effect reciprocation of said carriage in a direction perpendicular to the ads of rotation of the grinding wheel, said carriage slidably supporting a second carriage, said second carriage reciprocating with said firstnamed carriage and independently thereof in a direction parallel to th axis of rotation of the grinding wheel, means to effect said independent reciprocation of said carriage, a spindle mounted on said second carriage, said spindle adapted to support a gear to rotate with said spindle, means operatively associated with said spindle to effect rotation of the gear during independent reciprocation of said second carriage, the combined reciprocation of said second carriage and rotation of said gear causing said gear to roll as it enuses the annular teeth of the grinding wheel while the reciprocation of the first carriage causes the entire flank width of each gear tooth to con tact the grinding wheel, and feeding means to slidably move the grinding wheel toward and away from said work table.

17. In a gear grinding machine, a base, a grinding head mounted thereon, said head including a rotatable grinding wheel of substantial axial length; said grinding wheel having a plurality of spaced annular teeth of a straight rack tooth form in cross-sectional profile, means to drive said wheel, a carriage slidably mounted on said base, driving means to effect reciprocation of said carriage in a direction perpendicular to the axis of rotation of the grinding wheel, said carriage slidably supporting a second carriage, said second carriage reciprocating with said first-named carriage and independently thereof in a direction parallel to the axis of rotation of the grinding wheel, means to effect said independent reciprocation of said carriage, a spindle mounted on said second carriage, said spindle adapted to mount a gear to be ground, and means operatively associated with said spindle to effect rotation of the gear during independent reciprocation of said second carriage, the combined reciprocation of said second carriage and rotation of said gear and spindle causing said gear to roll as it engages the annular teeth of the grinding wheel while the reciprocation of the first carriage causes the entire flank width of each gear tooth to contact the grinding wheel, and feeding means to slidably move the grinding wheel toward and away from the gear in a direction perpendicular to the rotative axis thereof.

18. In a gear grinding machine, a base, a grinding head mounted on said base, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth of a straight rack tooth form in cross-sectional profile formed on the periphery thereof, means to rotatably drive said wheel, a carriage slidably mounted on said base, for movement toward and away from said grinding wheel in a direction perpendicular to the rotative axis thereof, means to effect predetermined reciprocation of said carriage, including a prime mover mounted on said base and an eccentric drivingly connected to said prime mover and operatively associated with said carriage, a second carriage slidably mounted on said first carriage for movement with said first carriage and for movement with respect to said first carriage in a direction parallel to the axis of rotation of the grinding wheel, means to efi'ect said independent reciprocation of said second carriage including a shaft rotatably supported in said first carriage, means supported on said first carriage for rotating said shaft, gear means fixed to one end of said shaft, rack means on said second carriage meshing with said gear means on said shaft, 2. spindle rotatably supported in said second carriage, said spindle adapted to rotatably support a gear, a master gear fixed to said spindle, a master rack fixed to said first carriage and meshing with said master gear to effect rotation of said spindle and gear upon reciprocation of said second carriage, the combined reciprocation and rotation of said spindle effecting the gear to roll as it engages the annular teeth of the grinding wheel while the reciprocation of the first carriage effects the entire flank width of each gear tooth to contact the grinding wheel.

19'. In a gear grinding machine, a base, a grinding head mounted on said base, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth formed on the periphery thereof of a straight rack tooth form in cross sectional profile, carriage means mounted on said base for reciprocation in a direction perpendicular to the axis of rotation of said wheel andin a direction parallel to the axis of rotation of said wheel, means rotatably supportwith said gear causing said gear to roll as it engages said wheel while the perpendicular reciprocation of said carriage means causes the entire flank width of each gear tooth to contact the grinding wheel, and index means to efiect indexing rotation of said gear after the same has been reciprocated in said parallel direction out of engagement with said grinding wheel.

20. In a gear grinding machine, a base, a grinding head mounted on said base, said head including a rotatable grinding wheel of substantial axial length, said grinding wheel having a plurality of axially spaced annular teeth of a straight rack tooth form in cross-sectional profile formed on the periphery thereof, carriage means mounted on said base for reciprocating said gear in a direction perpendicular to said grinding wheel and in a direction parallel to said grinding wheel, means for rotatably supporting a gear to be finished in said carriage means so that said gear is engageable by said grinding wheel, means for rotating said gear during said parallel reciprocation of said carriage means so as to cause said gear to roll as it engages said wheel while the' perpendicular reciprocation of said carriage means causes the entire flank width of each gear tooth to contact the grindin wheel, and index means to effect indexing rotation of said gear after the same has been reciprocated in said parallel direction beyond engagement with said grinding wheel.

MARVIN R. ANDERSON.

REFERENCES CITED The following references are of. record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,642,554 Olson Sept. 13, 1927 1,693,781 Hanson Dec. 4, 1928 1,811,933 Hohnhorst et al. June 30, 1931 1,832,507 Schurr Nov. 17, 1931 1,909,398 Garrison May 16, 1933 2,022,061 Tanner Nov. 26, 1935 2,385,650 Richenmann Sept. 25, 1945 FOREIGN PATENTS Number Country Date 533,736 Germany Sept. 19, 1931 

